This invention relates to a process of reducing exhaust emissions of diesel fueled internal combustion engines, and more particularly to the use of rare earth metal compounds to reduce the amount of particulates in diesel engine exhaust emissions.
Diesel fueled internal combustion engines give off particulates in the exhaust which may be harmful pollutents. These particulates are both particules seen as visible smoke and also are those particles which are invisible but still present in the diesel exhaust. The Federal Environmental Protection Agency has recently determined that diesel powered automobiles emit unacceptably high levels of air pollution and the levels of particulate emissions must be reduced to about 0.2 gram per mile by 1985. Presently most diesel engines used in automobiles will probably exceed this limit.
Various additives have been suggested for use in diesel fuels to reduce particulate emissions. U.S. Pat. Nos. 2,926,454; 3,410,670; 3,413,102; 3,539,312 and 3,499,742 are representative patents which show smoke suppressants which are commonly employed in or added to the diesel fuel oils. In general, the previously used most common smoke suppressants employed an organic compound of barium. Calcium compounds have also been proposed to replace the barium materials previously suggested because of the possibility of the toxicity of the barium.
Coassigned U.S. Pat. No. 4,207,078 sets forth a reduction in soot and visible particulate matters from the exhaust of diesel fueled engines by incorporating within the diesel fuel an additive consisting of a mixture of an oxygenated compound and an alkyl cyclopentadienyl manganese tricarbonyl.
Coassigned U.S. Pat. No. 4,222,746 sets forth the addition of wax oxidates to diesel fuel along with a fuel soluble organometallic compound such as alkyl cyclopentadienyl manganese tricarbonyl complex salts. The combined effect of these two additives reduces the soot and visible particulates emitted from the exhaust of diesel fueled internal combustion engines.